HD 11343 c
Astrophysical Synthesis & Habitability Characterization
HD 11343 c is a confirmed gas giant exoplanet orbiting the star HIP 8541, located approximately 505.9 light-years (155.12 parsecs) from the Solar System. First announced in 2022 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.9 Earth radii (1.24 Jupiter radii) and has a measured mass of 255.534 Earth masses (0.8 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.52 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.32 g⊕ (12.94 m/s²), and an escape velocity of 48 km/s.
In its orbital architecture around HIP 8541, HD 11343 c completes one full revolution every 228.537 Earth days at a semi-major axis of 0.923 AU (comparable to the inner terrestrial zone between Venus, Earth at 1.00 AU, and Mars at 1.52 AU). Its mean orbital velocity is approximately 43.9 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.169 carries the world between 0.767 AU at periapsis and 1.079 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 613 K (+340°C / +644°F) and receiving 23.97 S⊕ (~32,618 W/m²), HD 11343 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HIP 8541 is classified as an orange K-type star of spectral type K2 III/IV with an effective photospheric temperature of 4,672 K, a radius of 6.84 R☉, a mass of 2.009 M☉, an estimated bolometric luminosity of 19.999 L☉. Stellar evolution modeling indicates an estimated stellar age of 10.97 Gyr and a metallicity of [Fe/H] = -0.19 dex (metal-poor relative to the Sun). From Earth, HIP 8541 shines at apparent V-band magnitude 7.88 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HIP 8541 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 11343 c sharing its stellar neighborhood alongside HIP 8541 b.
Methodology: Computed using the Schulze-Makuch et al. (2011) weighted metric comparing physical interior (radius, estimated density) and surface thermal regime (escape velocity, equilibrium temperature).
Discovery Facility: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HIP 8541 |
| Spectral Type | K2 III/IV |
| Effective Temp (Teff) | 4,672 K |
| Stellar Radius | 6.8400 R☉ |
| Stellar Mass | 2.0090 M☉ |
| Bolometric Luminosity | 19.999 L☉ |
| Metallicity [Fe/H] | -0.190 dex |
| Stellar Age | 10.970 Gyr |
| Apparent Magnitude | V: 7.880 · G: 7.561 |
| System Architecture | 2 Stars, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.923000 AU |
| Orbital Period | 228.537 days |
| Mean Orbital Velocity | 43.9 km/s |
| Orbital Eccentricity (e) | 0.16900 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.52 g/cm³ (48 km/s vesc) |
| Insolation Flux | 23.9661 S⊕ (~32,618 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 505.900 LY (155.121 pc) |